The present invention relates to a home network and more particularly to a method and an apparatus for optimizing the resource sharing for audio, video and data processing devices in a home network environment. This home network may comprise a plurality of set top units, data processing units, video and audio devices, and more particularly digital video processing devices.
The environment from which the present invention is derived is the digital video broadcasting (DVB) a detailed specification of which is given in the Standards. One may refer for instance to the European Telecommunication Standards Institute (ETSI) relating to the Digital Video Broadcasting published in EN 300 468-v1.3.1 (1997-09). Any other digital video broadcasting specification may be used.
In order to have an example of a home network implementation, one may refer to a U.S. Pat. No. 5,172,109, where  less than  less than a method for registering a unit in a home network at least one part of which is constituted from an open channel greater than  greater than  is disclosed. In that patent, a home automation network comprises open channels wherein various units are linked to the network. These units are for instance domestic electrical equipment, audio, video equipment etc. This particular environment can also be used with the present invention.
However, in the present case, we will consider only the domestic appliances that relate to the multimedia equipment that combines the video, audio and/or data transmissions. This equipment uses more specifically the digital video broadcast (DVB) specifications, their protocols and standards.
According to these requirements, when a DVB receiver tunes a DVB service, it physically tunes a given transponder which carries many DVB services in a multiple Program Transport Stream (MPTS). The associated demultiplexer extracts, through its digital filters the different sections relating to the expected services. Afterwards, the DVB receiver builds from these different sections a Single Program Transport Stream (SPTS) and broadcasts it onto the home network.
Therefore, the problem is to determine the number of DVB receivers, also called receiving means, according to the number of processing units, also commonly called Set Top Units (STUs), that are connected in the home network. A possible solution would be to use as many source devices as there are viewing devices. The source devices and the viewing devices are for instance respectively the DVB receivers and the STUs as previously quoted. In a particular implementation, the STUs are for instance the television sets with MPEG2 decoding capabilities or any other electrical devices that use the video, audio or data transmission.
In the prior art, the home networks often have a basic configuration in which to each set top unit (STU) corresponds a DVB receiver. The reason of this basic configuration is that if a STU needs to view a service other than the one  less than  less than tuned greater than  greater than  by a DVB receiver, an additional DVB receiver is required. This configuration implies that there is no sharing of the DVB receivers among the STUs. Therefore, one must acknowledge that this kind of configuration is very expensive and the consumers are certainly not willing to spend so much to settle this home network configuration.
Consequently, it would be preferable to share the source devices or the also called DVB receivers among all the STUs that are connected to the home network and to optimize this resource sharing. In all the description that follows, a video/audio/data processing unit may be represented by a STU.
It is a primary object of the invention to reduce the number of receiving means by avoiding implementing in a digital home network as many receiving means (or source devices) as there are video/audio/data processing units such as Set Top Units.
It is also an object of the invention to optimise the resource sharing of the receiving means among a plurality of video/audio/data processing units such as Set Top Units.
It is another object of the invention to allot a priority to a specific processing unit in the home network.
It is further object of the invention to control and to track the services tuned by a specific processing unit.
According to the present invention, the services can be shared by a plurality of video/audio/data processing units connected to the home network with respect to a Master/Slave protocol. A processing unit such as a STU may have access, with some constraints, to services that are offered to the principal (or Master) processing unit or STU on the same transport stream.
The principle of sharing the resource is based on the Master/Slave protocol according to which the priority is given to the Master processing unit over the Slave processing unit. The first processing unit or STU that is connected to a receiving unit or a DVB receiver becomes the Master of this DVB receiver.
The resource sharing complies to the two following principles:
As long as there is an available receiving means, a processing unit will have access to all the services accessible by this receiving means;
If there are no more receiving means left, a processing unit may have access to all the services currently viewed by the other processing units and more specifically to all the services offered on the transponder that comprises the services currently viewed by said other processing units.
Thus, according to the present invention, a method for optimizing the resource sharing between set top units in a home network comprising at least one emitter for broadcasting video/audio/data signals, a plurality of means for receiving the signals comprises the steps of:
(a) assigning to each processing Unit connecting to the home network, one of the plurality of receiving means providing requested resource that is available, by conferring to each processing Unit a status of Master processing Unit;
(b) assigning to each newly connected processing Unit one of said plurality of receiving means providing requested resource that is available by conferring a status of Slave processing Units, when no receiving means providing requested service is available; and
(c) sharing the resource between Master STUs and Slave STUs in the home network so as to provide access to the requested resource for the Slave STUs.
Conversely, the method according to the present invention may be implemented in an apparatus that comprises
means for assigning to each Set Top Unit connecting to the home network, one of the plurality of receiving means providing requested resource that is available by conferring to each processing Unit a status of Master processing Unit;
means for assigning to each newly connected processing Unit one of said plurality of receiving means providing requested resource and for conferring a status of Slave processing Unit, when no receiving means providing requested resource is available; and
means for sharing the resource between Master processing units and Slave processing units in the home network so as to provide access to the requested resource for the Slave processing units.
Furthermore, in a particular implementation, the apparatus comprises control means dedicated for each processing unit for displaying resource that is available for the corresponding processing unit wherein the control means contains:
an indication of Slave status for resource that can be provided for the corresponding processing unit; and
a special indication for resource that is currently used by a corresponding processing unit.